This application claims the priority of German application 198 51 209.0, filed in Germany on Dec. 9, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a backrest for vehicle seats comprising a backrest frame, a backrest cushion which is fastened to the backrest frame, a foamed cushion layer, a ventilation layer which covers the cushion layer formed as a coarse-mesh spaced knit through which air flows, and a ventilator fan for the active ventilation of the backrest cushion.
In the case of a known backrest of this type (German Patent Document DE 196 28 688C1), the backrest cushion is normally constructed with a backrest surface and two lateral edge elevations. Between the backrest cushion and an air-tight backrest rear wall, a hollow space is constructed which is open at the lower end of the backrest. In the hollow space, specifically close to the lower end of the backrest, a fan, which has an intake opening pointing to the open end of the hollow space, is arranged laterally in the area of an edge elevation. The blow-out opening of the fan is connected with a flexible duct which, in the surface area at the lower end of the backrest cushion, leads into its ventilation layer. The air delivered by the fan flows in the backrest surface area through the ventilation layer in order to ventilate the seat surface by way of the breathing cushion covering and to de humidify corresponding body regions of the seat user. The two edge elevations are ventilated separately by means of one miniature fan respectively, which are inserted into air ducts cut into the cushion layer and also take in air from the hollow space.
A known backrest for motor vehicle seats (German Patent Document DE 29 47 472 C2) has a support part, the so-called lordosis support, which is constructed as a flat curved section and, in an adaptation to the seat user's spinal column, is curved toward the front, one end of this support part being assigned directly to the backrest frame and the other end of the support part being supported on the backrest frame by means of an adjusting device which influences the curvature of the arch of the support part and has a horizontal-axis drive which acts upon the adjusting elements, in which case the adjusting elements act upon the upper end of the support part in the sense of a curvature change and act upon the vertex area of the support part in the sense of a position change of the vertex of the curvature.
A vehicle seat is known which has an active ventilation of the seat surface by means of a ventilator arranged below the seat cushion (German Patent Document DE 297 18 853 U1), in the case of which fastening devices are provided such on the fan housing or ventilator housing that they can be hung in a form-locking manner into spring bars which are disposed under the seat cushion, are bent in a meander-shaped manner and are used for the spring suspension of the seat.
It is an object of the invention to design a vehicle seat of the initially mentioned type, which is to be equipped with a lordosis support, with respect to an active ventilation of the backrest cushion, particularly of the backrest surface, at reasonable cost.
According to the invention this object is achieved by providing an arrangement of the above-noted type, wherein a mechanical lordosis support, which can be adjusted for an adaptation to the spinal column curvature of a seat user is fastened to the backrest frame, and wherein the fan is fastened largely centrally in the cushion area on the lordosis support at low vibrations such that it moves along without force in any adjustment of the lordosis support and in this case remains within an air duct sufficiently dimensioned for this purpose in the clear cross-section, which air duct penetrates the cushion layer from its rearward side facing the lordosis support to the ventilation layer.
The backrest according to the invention has the advantage that, despite the presence of the lordosis support, the fan can be placed centrally in the backrest cushion and therefore has an optimal position for the whole-surface uniform cushion ventilation so that a single fan is sufficient for the active cushion ventilation. The fan is installed without force so that, in the sat-in condition of the vehicle seat, it is subjected to no deformation and pressure forces and can therefore not be damaged. As the result of the elastic connection of the fan with the lordosis support and the good uncoupling of the lordosis support with respect to the backrest frame and, because of the fact that the fan does not come in direct contact with the backrest cushion, no special measures are required for damping vibrations. The fan is easily mountable and is easily accessible by way of the lordosis support so that it can easily be exchanged in the event of a repair.
Advantageous embodiments of the backrest according to the invention with expedient developments and further developments of the invention are found in the additional claims.
According to a preferred embodiment of the invention, the ventilator is elastically fastened on two transversely spaced, forward-arched longitudinal struts of the lordosis support whose arching degree can be adjusted and which receive transverse struts used for supporting the seat user's back. This has the advantage that, when the lordosis support is adjusted, the fan moves along without force, moving in the area of the air duct without leaving it or pressing against the cushion layer.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.